It is proposed to continue the development of systematic methods for the chemical synthesis of oligosaccharide structure from standard building-block derivatives of the component sugars, using a limited group of stereoselective coupling procedures. Trisacchrides having the general structure Gal(B,1) GlcNAc (B,1) Gal are currently "under constuction" (and nearing completion) in our laboratory. Specific objectives for the coming grant period are: (i) further illustrate the utility of our standard building-blocks by elaborating one of the foregoing trisaccharides to the terminal pentasaccharide (type 1) of human blood group substance B; (ii) undertake the synthesis of some of the Gal-GlcNAc-Gal trisaccharides, or other oligosaccharides, by the "solid-phase" method; (iii) synthesize additional building-blocks for the assembly of large segments of the core structure of the asparagine-linked glycoprotein oligosaccharides (collaboration with C.D. Warren); (iv) undertake the synthesis of specific oligosaccharides for use in biochemical investigations, when such syntheses would allow us to develop some new chemistry; and (v) develop new chemistry of building-block synthesis or coupling that would serve predictable future needs. The relative priorities assigned to objectives i, ii, and iii will depend on the results of experiments with the solid-phase method now under way in our laboratory.